Why is this called Reversi and not Othello?

"Othello" is a registered trademark for a specific commercial edition of the game. The underlying rules are traditional and unencumbered, and Reversi is the original public-domain name, dating to the 1880s. So that is the name used here.

Is it bad to have more discs in the middle of the game?

Usually, yes. Holding fewer discs tends to mean you have more safe moves available and your opponent has fewer. Experienced players deliberately keep their disc count low until the last ten or so moves.

What happens if I have no legal move?

Your turn is skipped automatically and your opponent moves again. If neither side can move, the game ends there and the discs are counted, even if the board is not full.

Does the first player have an advantage?

Not a decisive one. With perfect play the game is a draw. Black’s first move is a small practical edge at club level, but far less than Black’s advantage in Gomoku.

How strong is the AI on this page?

The higher levels search several moves deep with a mobility- and stability-aware evaluation, and solve the final twelve to eighteen empty squares exactly. Level 4 will beat most casual players comfortably.

Play Reversi Online Free vs AI — Rules, Corner Strategy & Mobility Tactics

How to play Reversi

1Reversi is played on an 8×8 board. The four central squares start filled: two black discs and two white discs, placed diagonally. Black moves first.
2A legal move places one disc so that it outflanks at least one straight line of the opponent’s discs — that is, there is an unbroken row of enemy discs between your new disc and another of your discs, in any of the eight directions.
3Every enemy disc that is outflanked by the move flips to your colour. A single move can flip discs in several directions at once.
4If you have no legal move, your turn is skipped and the opponent moves again. If neither player has a legal move, the game ends immediately.
5The game also ends when the board is full. Whoever has more discs of their colour on the board wins; an equal count is a draw.
6You may never pass voluntarily. If a legal move exists, you must play one.

Reversi strategy guide

Corners are permanent, everything else is not

A disc in a corner can never be outflanked, because there is no square beyond it. Corners are the only truly stable squares on an empty board, and they anchor whole edges. Winning a corner is usually worth more than a dozen discs elsewhere.

Never touch the X-squares early

The four diagonal neighbours of the corners — c3, f3, c6, f6 in standard notation — are called X-squares. Playing one usually hands your opponent the adjacent corner. The squares directly beside a corner (the C-squares) are nearly as dangerous.

Fewer discs is better in the middlegame

This is the counter-intuitive heart of Reversi. The player with fewer discs typically has more legal moves available and forces the opponent into bad ones. Flipping a huge number of discs in move twenty usually just gives your opponent more edges to attack.

Mobility is the real currency

Count how many legal moves each side has. If you can keep your options open while shrinking your opponent’s, they will eventually be forced to play an X-square or hand you a corner. Quiet moves that flip one or two interior discs are often the strongest.

Switch to counting in the endgame

With roughly twelve empty squares left, positional thinking gives way to exact calculation — the final disc count is all that matters. The engine here solves the last dozen squares perfectly, so a "safe" positional lead can evaporate on the final move.

The history of Reversi

Reversi was invented in England around 1883. Two men, Lewis Waterman and John W. Mollett, each claimed to have created it and spent years publicly disputing the other’s claim; the game was published commercially by Jaques of London and became a Victorian parlour staple.

The modern competitive form dates to 1971, when Goro Hasegawa standardised the fixed starting position and 8×8 board in Japan and marketed it under a name that is now a registered trademark. That commercial edition drove an enormous boom in Japan and a serious tournament scene, which is why the strongest human players and the deepest opening theory are still largely Japanese.

Reversi has also been a landmark for computer game playing. The program Logistello defeated the reigning world champion Takeshi Murakami 6–0 in 1997, and modern engines solve the 8×8 game far beyond human reach. In 2023 the game was weakly solved: with perfect play by both sides, Reversi on the standard board is a draw.

Reversi FAQ

Why is this called Reversi and not Othello?: "Othello" is a registered trademark for a specific commercial edition of the game. The underlying rules are traditional and unencumbered, and Reversi is the original public-domain name, dating to the 1880s. So that is the name used here.
Is it bad to have more discs in the middle of the game?: Usually, yes. Holding fewer discs tends to mean you have more safe moves available and your opponent has fewer. Experienced players deliberately keep their disc count low until the last ten or so moves.
What happens if I have no legal move?: Your turn is skipped automatically and your opponent moves again. If neither side can move, the game ends there and the discs are counted, even if the board is not full.
Does the first player have an advantage?: Not a decisive one. With perfect play the game is a draw. Black’s first move is a small practical edge at club level, but far less than Black’s advantage in Gomoku.
How strong is the AI on this page?: The higher levels search several moves deep with a mobility- and stability-aware evaluation, and solve the final twelve to eighteen empty squares exactly. Level 4 will beat most casual players comfortably.

Reversi